The present invention relates to materials and methods for assisting in the healing of avulsed, burned, or ablative wounds, and in particular, to materials and methods which prevent excessive cicatricial, keloid, or fibromatoid formation, reduce fluid loss and provide protection from infection.
The treatment of open wounds has been hampered by a number of factors. It is desirable, for example, that such open wounds be protected against both infection and fluid loss by covering the wounds with a dressing. Dressings of fibrous material may actually interfere with the healing of the wound by becoming incorporated with the scab or granulation tissue and thus necessitating later surgical removal from the wound. Dressings of synthetic film have been employed but may also interfere with the healing of the wound by causing excessive accumulation of fluid beneath the dressing and may further interfere with healing since the body may tend to reject the synthetic material.
An additional problem with the healing of a large area wound is that of excessive scarring during the healing process. Various attempts have been made to address some or all of these problems.
U.S. Pat. No. 4,725,279 discloses a bio-and blood compatible material for a thermal burn dressing. The material is a composite comprising a thin film of thermoplastic material, such as Silastic .RTM. (Dow Corning), a knitted or woven layer, and a bonded layer of biological molecules to render the material bio-and blood compatible. It is disclosed that the material has a vapor transmission rate comparable to the human skin and that it is desirable that the wound site be closed as occlusively as possible without allowing liquid to accumulate between the wound surface and the material of this invention. To avoid this effect a variant embodiment provides for "pinholes" in the material such that the material remains 98% or better occlusive.
U.S. Pat. No. 4,838,253 discloses a liquid permeable dressing comprising one or more sheets of apertured material, such as cotton gauze, coated with a tacky silicone gel or a non-tacky silicone elastomer.
U.S. Pat. No. 5,395,305 discloses a wound-covering material comprising two layers: a first support layer which is in contact with the wound and which contains a water repelling substance and a second moisture permeation controlling layer which may be formed from steam permeable resin films made of silicone or polyurethane elastomers.
U.S. Pat. No. 2,693,438 discloses a non-adherent pliable film for a surgical dressing. The dressing film is formed from water-soluble polyvinyl alcohol mixed with a plasticizing agent and water. The film may be reinforced by embedding a textile material in the outer layer. It is specifically noted that the film will not irritate the lesion or become incorporated in the scab or granulation tissue formed therein.
U.S. Pat. No. 5,196,190 discloses a membrane suitable for wound dressing comprising a natural or synthetic polymer, a non-gellable polysaccharide and a cross-linking agent. The membranes may also contain water-loss control agents, emulsifying agents, plasticizers, or an internal reinforcing material.
U.S. Pat. No. 3,803,300 discloses an ointment foil for application to skin. The ointment foil is prepared by drying an oil-in-water emulsion of ointment ingredients to a moisture content of 1% to 15%.
U.S. Pat. No. 3,867,520 discloses a medicated polyamino acid film for occlusive dressing therapy.
The limitations of the prior art are overcome by the present invention as described below.